Touch screens are used as a kind of input medium, which are a simple, convenient, and a natural way of human-computer interaction. Liquid crystals are increasingly used in display panels due to good electrical controllability. Therefore, touch screens are usually integrated in liquid crystal display panels so as to form a variety of electronic products, such as mobile phones, laptops, MP3/MP4, and so on.
A conventional in-cell touch screen achieves a touch sensing by sharing a common electrode with a display. FIG. 1 is a structural schematic diagram of the conventional in-cell touch screen including a color filter substrate and an array substrate. The color filter substrate includes a first glass substrate 101, a color resist layer 102, and a black matrix 103. The array substrate includes a second glass substrate 104, a buffer layer 105, a gate insulating layer 106, an interlayer insulating layer 107, a planarization layer 108, a common electrode layer, a dielectric layer 109, sensing electrode wires 110, a passivation layer 111, and a pixel electrode 114, all of which are stacked in sequence. The sensing electrode wires are connected with the common electrode layer through vias 112. The common electrode layer is patterned to form a number of electrode plates 113. A gap between the electrode plates 113 is formed and located directly below the black matrix 103. No electrode layer is between the electrode plates 113, and accordingly, no electrical field is in an area corresponding to the gap between the neighboring electrode plates. Therefore, a rotational direction of the liquid crystals at a location with no electrical field is inconsistent with a rotational direction of the liquid crystals in other places thereby inducing display brightness in the location with no electrical field to be inconsistent with display brightness in other places, and a display problem appears. Although the location with no electrical field is shielded by the black matrix 103, a display difference can still be viewed at a large oblique angle. Specifically, a bright line pattern or a dark line pattern is shown specifically, and a display effect is affected.
Further, horizontal light shielding strips in the black matrix 103 are used to shield thin film transistors and scan lines, where width of the horizontal light shielding strips is greater than width of vertical light shielding strips used to shield data lines. Therefore, the display problem of the bright line pattern or the dark line pattern appearing is mainly shown in an area corresponding to the vertical light shielding strips.
As mentioned above, since the conventional in-cell touch screen has no common electrode in a shielding area of the array substrate corresponding to the black matrix 103 so that liquid crystal molecules corresponding to the shielding area are flipped abnormally, the brightness in the shielding area is different from brightness in other areas. Therefore, the bright line pattern or the dark line pattern appears in the liquid crystal display panels when viewed from a large viewing angle, and a viewing effect is affected.